# JEE Main > Dual Nature of Matter and Radiation

Explore popular questions from Dual Nature of Matter and Radiation for JEE Main. This collection covers Dual Nature of Matter and Radiation previous year JEE Main questions hand picked by popular teachers.

Physics
Chemistry
Maths

Q 1.

Correct4

Incorrect-1

Sodium and copper have work functions 2.3 eV and 4.5 eV respectively. Then the ratio of the wavelengths is nearest to

A

1:2

B

4:1

2:1

D

1:4

##### Explanation

Q 2.

Correct4

Incorrect-1

Two identical photocathodes receive light of frequencies {tex} f _ { 1 } {/tex} and {tex} f _ { 2 } {/tex}. If the velocities of the photoelectrons (of mass {tex} m ) {/tex} coming out are respectively {tex} v _ { 1 } {/tex} and {tex} v _ { 2 } , {/tex} then

{tex} v _ { 1 } ^ { 2 } - v _ { 2 } ^ { 2 } = \frac { 2 h } { m } \left( f _ { 1 } - f _ { 2 } \right) {/tex}

B

{tex} v _ { 1 } + v _ { 2 } = \left[ \frac { 2 h } { m } \left( f _ { 1 } + f _ { 2 } \right) \right] ^ { \frac { 1 } { 2 } } {/tex}

C

{tex} v _ { 1 } ^ { 2 } + v _ { 2 } ^ { 2 } = \frac { 2 h } { m } \left( f _ { 1 } + f _ { 2 } \right) {/tex}

D

{tex} v _ { 1 } - v _ { 2 } = \left[ \frac { 2 h } { m } \left( f _ { 1 } - f _ { 2 } \right) \right] ^ { \frac { 1 } { 2 } } {/tex}

##### Explanation

Q 3.

Correct4

Incorrect-1

According to Einstein's photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal {tex} v s {/tex} the frequency, of the incident radiation gives a straight line whose slope

A

depends on the nature of the metal used

B

depends on the intensity of the radiation

C

depends both on the intensity of the radiation and the metal used

is the same for all metals and independent of the intensity of the radiation.

##### Explanation

Q 4.

Correct4

Incorrect-1

The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately

A

{tex} 540 \mathrm { nm } {/tex}

B

{tex} 400 \mathrm { nm } {/tex}

{tex} 310 \mathrm { nm } {/tex}

D

{tex} 220 \mathrm { nm} {/tex}

##### Explanation

Q 5.

Correct4

Incorrect-1

A charged oil drop is suspended in a uniform field of {tex} 3 \times 10 ^ { 4 } \mathrm { V } / \mathrm { m } {/tex} so that it neither falls nor rises. The charge on the drop will be (take the mass of the charge = 9.9 X 10 {tex}^ { - 15 } {/tex} kg and g = 10 m/s{tex} ^ { 2 }{/tex})

{tex} 3.3 \times 10 ^ { - 18 } \mathrm { C } {/tex}

B

{tex} 3.2 \times 10 ^ { - 18 } \mathrm { C } {/tex}

C

{tex} 1.6 \times 10 ^ { - 18 } \mathrm { C } {/tex}

D

{tex} 4.8 \times 10 ^ { - 18 } \mathrm { C } {/tex}

##### Explanation

Q 6.

Correct4

Incorrect-1

A photocell is illuminated by a small bright source placed {tex} 1 \mathrm { m } {/tex} away. When the same source of light is placed {tex} ( 1 / 2 ) {/tex} m away, the number of electrons emitted by photocathode would

A

decrease by a factor of 2

B

increase by a factor of 2

C

decrease by a factor of 4

increase by a factor of 4

##### Explanation

Q 7.

Correct4

Incorrect-1

If the kinetic energy of a free electron doubles, its de Broglie wavelength changes by the factor

{tex} 1 / \sqrt { 2 } {/tex}

B

{tex} \sqrt { 2 } {/tex}

C

{tex} 1 / 2 {/tex}

D

{tex} \mathrm 2{/tex}

##### Explanation

Q 8.

Correct4

Incorrect-1

The time by a photoelectron to come out after the photon strikes is approximately

A

{tex} 10 ^ { - 1 } \mathrm { s } {/tex}

B

{tex} 10 ^ { - 4 } \mathrm { s } {/tex}

{tex} 10 ^ { - 10 } \mathrm { s } {/tex}

D

{tex} 10 ^ { - 16 } \mathrm { s } {/tex}

##### Explanation

Q 9.

Correct4

Incorrect-1

The threshold frequency for a metallic surface corresponds to an energy of {tex} 6.2 \mathrm { eV } , {/tex} and the stopping potential for a radiation incident on this surface {tex} 5 \mathrm { V } {/tex}. The incident radiation lies in

A

X-ray region

ultra-violet region

C

infra-red region

D

visible region.

##### Explanation

Q 10.

Correct4

Incorrect-1

The anode voltage of a photocell is kept fixed. The wavelength {tex} \lambda {/tex} of the light falling on the cathode is gradually changed. The plate current {tex} I {/tex} of the photocell varies as follows

A

B

D

##### Explanation

Q 11.

Correct4

Incorrect-1

Photon of frequency {tex} v {/tex} has a momentum associated with it. If {tex} c {/tex} is the velocity of light, the momentum is

{tex} h \nu / c {/tex}

B

{tex} \nu / c {/tex}

C

{tex} h\nu c {/tex}

D

{tex} h v / c ^ { 2 } {/tex}

##### Explanation

Q 12.

Correct4

Incorrect-1

If {tex} g _ { E } {/tex} and {tex} g _ { M } {/tex} are the accelerations due to gravity on the surfaces of the earth and the moon respectively and if Millikan's oil drop experiment could be performed on the two surfaces, one will find the ratio $\frac { \text { electronic charge on the moon } } { \text { electronic charge on the earth } } \text { to be }$

A

{tex} g _ { M } / g _ { E } {/tex}

1

C

0

D

{tex} g _ { E } / g _ { M } {/tex}

##### Explanation

Q 13.

Correct4

Incorrect-1

Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure)

Electrons accelerated by potential {tex} V {/tex} are diffracted from a crystal. If {tex} d = 1 \mathrm { A } {/tex} and {tex} i = 30 ^ { \circ } , V {/tex} should {tex} \mathrm { d } \mathrm { d } {/tex} be about {tex} \left( h = 6.6 \times 10 ^ { - 34 } \mathrm { Js } , m _ { e } = 9.1 \times 10 ^ { - 31 } \mathrm { kg } , \right. {/tex} {tex} \left. e = 1.6 \times 10 ^ { - 19 } \mathrm { C } \right) {/tex}

A

{tex} 1000 \mathrm { V } {/tex}

B

{tex} 2000 \mathrm { V } {/tex}

{tex} 50 \mathrm { V } {/tex}

D

{tex} 500 \mathrm { V } {/tex}

##### Explanation

Q 14.

Correct4

Incorrect-1

Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure)

If a strong diffraction peak is observed when electrons are incident at an angle {tex} i {/tex} from the normal to the crystal planes with distance {tex} d {/tex} between them (see figure), de Broglie wavelength {tex} \lambda _ { d B } {/tex} of electrons can be calculated by the relationship {tex} ( n {/tex} is an integer)

A

{tex} d \cos i = n \lambda _ { d B } {/tex}

B

{tex} d \sin i = n \lambda _ { d B } {/tex}

{tex} 2 d \cos i = n \lambda _ { d B } {/tex}

D

{tex} 2 d \sin i = n \lambda _ { d B } {/tex}

##### Explanation

Q 15.

Correct4

Incorrect-1

Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure)

In an experiment, electrons are made to pass through a narrow slit of width {tex} d {/tex} comparable to their de Broglie wavelength. They are detected on a screen at a distance {tex} D {/tex} from the slit.

Which of the following graphs can be expected to represent the number of electrons {tex} N {/tex} detected as a function of the detector position {tex} y ( y = 0 {/tex} corresponds to the middle of the slit)?

B

C

D

##### Explanation

Q 16.

Correct4

Incorrect-1

If {tex} g _ { E } {/tex} and {tex} g _ { M } {/tex} are the accelerations due to gravity on the surfaces of the earth and the moon respectively and if Millikan's oil drop experiment could be performed on the two surfaces, one will find the ratio $\frac { \text { electronic charge on the moon } } { \text { electronic charge on the earth } } \text { to be }$

A

{tex} g _ { M } / g _ { E } {/tex}

1

C

0

D

{tex} g _ { E } / g _ { M } {/tex}